In the related art, an earphone socket is used as a main adapter for electrical signal transmission in all types of electronic products, specially provided as an audio connector for audio signal output/input and more widely applied in various kinds of audiovisual products. In particular, with the rapid development of a variety of portable electronic products, such as mobile phones, personal digital assistants (PAD), MP3 players, recording pens, and notebook computers, earphones with various sizes have been extensively used in those products in recent years.